1. Field of the Invention
The present invention relates to a multimedia communication system comprising a plurality of mobile wireless communication terminals and a network for interconnecting each of the mobile wireless communication terminals; and in more particularly to a method of transmitting and receiving multimedia messages that are composed of data of a plurality of media types between mobile wireless communication terminals.
2. Description of the Related Art
In recent years, the capability to transmit and receive messages such as text between mobile wireless communication terminals such as mobile telephones has been widely used. FIG. 1 shows the configuration of such a mobile telephone system of the prior art. In FIG. 1, the mobile wireless communication terminals are assumed to be mobile telephones.
As shown in FIG. 1, the mobile telephone system of the prior art comprises: mobile telephones 110 and 120; HLR (home location register) 40 which is a database for registering subscriber information of subscribers to the mobile telephone system and information such as positional information of mobile telephones whose powers are turned on; mail server 150; and network 60. Network 60 comprises a base station, a base station control device, and the like and interconnects mobile telephones 110 and 120 as well as HLR 40 and mail server 150.
A procedure for transmitting a message from mobile telephone 110 to mobile telephone 120 in the mobile telephone system of the prior art will be explained below with reference to the sequence chart of FIG. 2.
Mobile telephone 110 first transmits a message addressed to mobile telephone 120 to mail server 150 by way of network 60. Mail server 150 holds the message from mobile telephone 110 and notifies mobile telephone 120 of the incoming call. When received the notification of the incoming call from mail server 150, mobile telephone 120 checks the content of the message that has been transmitted, and requests mail server 150 for reception. After receiving the reception request from mobile telephone 120, mail server 150 transmits the content of the message that it holds to mobile telephone 120. Finally, after receiving the message from mail server 150, mobile telephone 120 transmits a reception recognition notice indicating that the message has been received to mobile telephone 110 by way of network 60.
The mobile telephone system of the prior art enables transmission and reception of messages between each of the mobile telephones. However, the slow transmission rates of wireless communication methods that are employed in mobile telephone systems that are now in practical use has complicated the transmission and reception, as messages, of bulky data such as dynamic images. The type of data that can be transmitted and received as a message has therefore been limited to data such as text data. When a static image is added to text data, the format is set for each media type and transmission and reception is possible only by means of the set format.
The anticipated adoption of wireless communication methods such as the CDMA (Code Division Multiple Access) communication method in the next-generation mobile telephone systems will increase data transmission rates. In these next-generation mobile telephone systems, it will be possible to transmit and receive a variety of data including text, graphics, video, and audio, as messages.
In a multimedia message service (MMS) that can transmit and receive data of a plurality of media types as messages, it is expected that data of various types of formats, though the same video data, will be transmitted and received as messages.
In a multimedia communication system that offers this MMS, moreover, it is expected that connecting an external terminal to a mobile wireless communication terminal such as a mobile telephone will enable an extension of the range of media types and formats that can be received.
Despite the realization of this type of MMS, however, it will still not be possible for a mobile wireless communication terminal that is the origin of transmission to detect the types of data that can be received as a message at the mobile wireless communication terminals that are the destinations. Thus, when data of various media types and formats are transmitted and received as messages as in the prior art, there is the possibility for the occurrence of problems such as the inability of transmission-destination mobile wireless communication terminals to receive a multimedia message that has been transmitted from a particular mobile wireless communication terminal.
In particular, when the range of media types and data formats that can be received varies according to whether or not an external terminal is connected to the mobile wireless communication terminal, the current state of the destination mobile wireless communication terminals may prevent reception of a multimedia message of the same media type and data format as a multimedia message that was previously receivable. Thus, even a particular mobile wireless communication terminal has transmitted a multimedia message of the same media type and data format as a multimedia message that was previously receivable, transmission-destination mobile wireless communication terminals may in some cases be unable to receive the multimedia message.